A battery pack, as a power source of a wireless electric tool, limits the development of wireless electric tools. Battery packs typically have an output voltage below 30V, and usually lead to problems such as insufficient power and undesirable endurance upon driving large-power electric tools. Currently there is no charging assembly that has an output voltage above 30V and a circuit structure that can be safely used during charging. Likewise, currently there is no corresponding charging control method for such a charging assembly.